Studies are being carried out to evaluate the effects of intravenous nitroglycerin in patients with acute myocardial infarction. Animal studies are being carried out to determine the effects of nitroglycerin and other vasodilators on regional myocardial blood flow and collateral development. Nitroglycerin is also being investigated as an anti-arrhythmic agent in animals both with and without myocardial infarction. Noninvasive radioactive tracer studies with thallium 201 both at rest and exercise have been found to be more sensitive than standard exercise electrocardiography in detecting myocardial ischemia. New techniques are being developed to evaluate ventricular function and to determine ventricular volume curves by multiple gated acquisition (MUGA) techniques following IV injection of technetium 99m human serum albumin. Coronary angiographic and contrast ventriculographic studies are being used to help predict survival following acute myocardial infarction. The effects of mechanical resuscitation are being studied in patients with cardiac arrest and Tris buffer used to correct intracellular acidosis and improve ventricular function following cardiac arrest.